Spiller U.S. Pat. No. 4,236,262 discloses a spring assembly wherein there is a base frame, a grid frame and coils connected at their lower ends to the base frame and at their upper ends to the grid frame. The grid frame includes longitudinally and transversely-extending right angular crossing wires welded at their crossings. The transversely-extending wires are arranged in groups of three with relatively wide spaces between groups and the longitudinal wires are arranged singularly at a wider space transversely of the grid than the groups of three wires longitudinally of the grid. The effect of this arrangement is to provide a structure which is prone to sag longitudinally where the heaviest load is applied and wherein sagging is least desirable. One of the purposes of this invention is to provide an arrangement of grid wires which will be most resistant to sagging longitudinally in a plane where the load is greatest. A further object is to provide for attaching coils to the grid wires as thus arranged which will not require notching the top loops of the coils. Another object is to provide for attaching the coils in spaced or overlapping relation. A still further object is to provide for attaching the coils to the grid wires in both odd and even numbers without modifying the arrangement of wires, that is, to enable employing a grid with a specific arrangement of wires which will enable positioning the coils in a number of different patterns.